Squat next to the table
In this study they suggested that by squatting down next to the table it does at least three positive things: (1) it increases the congruence (an accord, a harmonious relation, an exact coinciding) between your and your guests posture, (2) brings your eye level down to the guests eye level (which facilitates eye contact) and (3) brings your face closer to the guests faces.
They even suggested that in less formal dining situations you may want to pull out a chair and sit at the table with the guest.
Now everyone agrees that making eye contact, being on the same level and being close to your guest is very important. But there is a problem with squatting or sitting at your guests table.
When you squat, where do you put your order pad? On the table! You do not want to lean on the guests table. What was the first thing your mother taught you about dining etiquette? Arms off the table of course.
And what about that linen napkin that many servers have tucked in their apron behind them, dragging on the floor while squatting, would you want your server handling your food with that?
It is much better to bow or bend your knees slightly when talking to your guests. This is much more professional and you are a professional.